236 



SYSTEMATIC ZOOLOGY 



t 



eggs are laid in yellow, hemispherical capsules, half a centimeter 

 or more in diameter, which adhere together in spherical balls 



about ten centimeters in diameter 

 (Fig. 241); they are called sea corn 

 by the New England fishermen. A 

 large snail, Fulgur 

 carica, has even more 

 conspicuous Qgg cap- 

 sules ( Fig. 242 ). They 

 consist of disc-shaped 

 cases with a circular 

 thin spot at one mar- 

 gin, marking the point 

 of exit of the embryos, 

 and at the opposite 

 diameter are attached F , lr - 24 °- Cre t* 



aula, a slipper lim- 

 FlG. 239. A keyhole limpet; shell to a Stalk, likewise pet. (Drawn from 

 seen from above. (Drawn from formed bv the smil specimen by the 



iei mien.) _ - ' author.) 



which may be from 

 sixty centimeters to nearly a meter in length. 



The most abundant snail along the New Fngland coast to- 

 day is the periwinkle, Littorina littoi'ea, which some years 

 ago was introduced from England into Halifax, whence it 



spread pretty rapidly 

 southward ; in England 

 it is a great article of 

 food. Along the sandy 

 shores of Xew England 

 the so-called sand collars 

 are very abundant in 

 summer time; these are 

 simply masses of eggs, 

 to which the sand ad- 

 heres, which have been 

 laid by a very large 

 snail, Natica heros, 



whose shell sometimes 

 FIG. 241. Mass of egg capsules of a marine snail, attains a diameter f 

 Buccinum ; reduced about one halt. ( Photo- 

 graphed from specimen by the author.) eight Centimeters ; its 





